The Australian also believes his side must concentrate for the whole game if they are to avoid conceding cheap goals.
Crawley went behind to a 50th minute goal headed by Hallam Hope.
Their hopes of a fightback were raised by the sending-off of Carlisle player Richie Bennett with 16 minutes to go.
But Crawley’s only shots on target came in the first half through Jordan Roberts and Jimmy Smith who were both denied by goalkeeper Jack Bonham.
He said: “We’ve got to take those chances at the end of the day and unfortunately the goals that we are letting in, our mistakes, are nothing we have worked in during the week because I don’t think you can coach that.
“You just have to be switched on 100 per cent of the time and make sure you do your job properly.
“It was frustrating because they (Carlisle) had one shot on target and one goal.
“It’s annoying but in football you have to concentrate and today you had to concentrate for 96 minutes and that moment you don’t concentrate: bang, goal.
“Carlisle came here to do a job and good luck to them.”
Reds’ boss explained the tactics needed to overcome a team reduced to ten men by a sending-off as was the case when Carlisle’s Richie Bennett was shown a red card with 16 minutes to go for elbowing Josh Yorwerth.
“We still have to play the right way to get it into the area and not get stuck in the channels.
“Because with ten men they make it nice and compact and make it very hard to break down.
“We have got to get the ball wide, make two v one overloads, drive the ball to the line, get people round the back and cut balls back and you never know what can happen; but we didn’t have that.”